WLAN LOW NOISE AMPLIFIER USING HBT TECHNOLOGY

AZLINA BINTI ABDUL LATIP

This report is submitted in partial fulfillment of requirements for the award of Bachelor Degree of Electronic Engineering (Telecommunication Electronic

Engineering) with honours

Faculty of Electronic and Computer Engineering Universiti Teknikal Malaysia Melaka

MAY 2008

UNIVERSTI TEKNIKAL MALAYSIA MELAKA FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

W

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA I1

Tajuk Projek : WLAN LOW NOISE AMPLIFIER DESIGN USING HRT

TECHNOLOGY

Sesi Pengajian

: 2007/2008

Saya AZLINA RINTI ARDUL LATIP

mengaku membenarkan Laporan Projek Sarjana Muda ini disimpan di Perpustakaan dengan syarat- syarat kegunaan seperti berikut:

1. Laporan adalah hakrnilik Universiti Teknikal Malaysia Melaka.

2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja.

3. Perpustakaan dibenarkan membuat salinan laporan ini sebagai bahan pertukaran antara institusi

pengajian tinggi.

4. Sila tandakan ( .\I ) :

SULIT*

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat terhad yang telah ditentukan oleh organisadbadan di mana penyelidikan dijalankan)

Disahk oleh- 2" -

L (TAN TANGAN PENULIS)

Alamat Tetap: 371 MK F PAYA KONGSI, 11000 BALIK PUI.AU, PULAU PMANG.

Tarikh: 09 MAY 2008 Tarikh: 09 MAY 2008

DECLARATION I

"I hereby declare that this report is result of my own effort except for works that

have been cited clearly in the references."

. . . . . . . . . . . . . . . . . . . . . . . . . . Author : AZLINA BINTI ABDUL ALTIP

Date : 09 MAY 2008

DECLARATION I1

" I hereby declare that I have read this report and in my opinion this report is

sufficient in terms of scope and quality for the award of Bachelor of Electronic

Engineering ( Telecommunication Electronics) With Honours"

a

,

Signature . . . . . . . . ......................... Supervisor's Name : ABD MAJID BIN DARSONO

Date : 09 MAY 2008

DEDICATION

To my beloved father and mother

ACKNOWLEDGEMENT

Praise to Allah has given me the strength, physical and mentally in order to

complete this thesis.

I would like to express my gratitude to my supervisor, Mr. Abd. Majid Bin

Darsono. .that assisted and helped me a lot from the beginning of this project until

this thesis is completely written.

Besides, I would like to take this opportunity to thanks to Telecommunication

Technician; Mr Azizi Osman and all Technicians at Projek Sarjana Muda (PSM)

laboratory and Microwave laboratory for their support and help that is valuable for

this thesis.

Last but not least, I would like to thanks to my friends and whoever involved

that contributed to the successhl of this thesis.

Thank you.

ABSTRACT

Demand for WLAN system is increasing and keep improving with new

technologies. One of the problems faced by WLAN system is noise caused by

propagation through air, electron movement and interfacing signal that degrade the

transceiver system performance. Then, this thesis presented a Low Noise Amplifier

(LNA) design to overcome the weak receive signal pick up by antenna. This thesis

shows the process done on the design simulation of Low Noise Amplifier with

important characteristics such as gain, noise figure (NF), stability, power

consumption and complexity. Advance Design System (ADS) is used to design and

simulate the LNA circuit for 2.4GHz. Method that used in this design is single stage

and BFP 640 NPN Silicon Germanium RF transistor by Infineon Technologies is

choose due to the simplest configuration offered for an amplifier design. Then, the

designed circuit is fabricated using FR4 board and to performance of the designed

has been tested using Network Analyzer. The design has successfully minimized the

noise figure and provides sufficient gain for WLAN transceiver system.

ABSTRAK

Permintaan terhadap sistem WLAN meningkat dari hari ke hari dengan

pelbagai teknologi barn. Salah satu masalah yang terdapat di dalam sistem WLAN

adalah hingar yang disebabkan oleh penyebaran melalui udara, pergerakan elektron

dan isyarat antaramuka yang merendahkan pencapaian sistem pemancar-penerima

tersebut. Seterusnya, tesis ini membentangkan tentang rekabentuk penguat hingar

yang bertujuan untuk mengatasi isyarat yang lemah pada penerima yang dihantar ke

antena. Tesis ini juga menunjukkan proses yang telah dilakukan untuk menyiapkan

simulasi rekabentuk penguat hingar rendah dengan beberapa ciri penting seperti

gandaan, angka hingar, kestabilan, penggunaan kuasa dan kekompleksan. Perisian

Advance Device Systme(ADS) digunakan untuk merekabentuk dan membuat simulasi

untuk litar penguat hingar rendah pada 2.4GHz. Kaedah yang digunakan ialah

rekabentuk peringkat pertama dan Transistor NPN Silicon Germanium BFP640 yang

dikeluarkan oleh Infineon Technologies dipilih berdasarkan ciri - ciri istimewa yang

ditawarkan untuk rekabentuk penguat. Kemudian, litar yang telah direkabentuk

dibina menggunakan papan jalur FR4 dan keupayaan rekabentuk tersebut diuji

dengan menggunakan Network Analyzer. Rekabentuk ini berjaya meminimumkan

sistem angka hingar ini dan menyediakan gandaan yang baik untuk sistem pemancar-

penerima WLAN.

TABLE OF CONTENTS

CHAPTER TITLE

PROJECT TITLE

VERIFICATION FORM

DECLARATION I

DECLARATION I1

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

ABSTRAK

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREWIATIONS

LIST OF APPENDICES

I INTRODUCTION

1.1 Introduction

1.2 Research Background

1.3 Problem Statement

1.4 Objectives

1.5 Scopes of Work

1.6 Thesis Structure

11 LITERATURE REVIEW

2.1 Low Noise Amplifier

PAGE

i

ii

iii

iv

v

vi

vii

viii

ix

xii

xiii

xv

xvii

Microwaves

2.2.1 Frequency Range

Wireless LAN

HBT Technology

2.4.1 History of SiGe Technology

2.4.2 SiGe HBT Operation

2.4.3 Amplifier Parameter

DC Biasing

Matching Technique

2.6.1 Stub Matching

2.6.2 Single-Stub Matching of Transmission

Lines to Loads

Noise Figure

S-Parameter

Single Stage Amplifier

Stability Consideration

111 PROJECT METHODOLOGY

3.1 Flow Chart of Project Methodology 24

3.2 Design and Simulation Development 26

3.2.1 Transistor Analysis And Theory 27

3.2.2 Software (Design Tool) 3 1

3.2.3 Circuit Diagram 3 2

3.3 Hardware Development 3 3

IV RESULT AND DISCUSSION

4.1 Introduction

4.2 Simulation Result

4.2.1 Transistor Design

4.2.2 DC Biasing

4.2.3 Matching Network Design 4 1

4.2.4 Noise Figure Simulation Result 45

4.2.5 Gain (S21) Simulation Result 45

4.2.6 Input Return Loss (S11) and Output Return

Loss (S2*) Simulation Result 46

4.3 Measurement Result 47

4.4 Analysis of Simulation and Measurement 5 0

V CONCLUSION

5.1 Conclusion

5.2 Future Works

REFERENCES

APPENDICES A - E

xii

LIST OF TABLES

NO TITLE PAGE

Comparison of CMOS with conventional and SiGe BJTs 14

Noise Figure, Tabular Data, Tested At Room Temperature 2 8

LNA Gain Compression at 244 1 MHz 29

Circuit Description of Low Noise Amplifier 3 2

Data of Input Return Loss, S1 4 8

Data of Output Return Loss, S22 49

Data of Input Return Loss,Sll for Measurement and Simulation 5 1

Data of Output Return Loss,Sz2 for Measurement and Simulation 52

Comparison between Specification Given and Simulation at

2.4GHz 5 3

xiii

LIST OF FIGURES

NO TITLE PAGE

System Level Diagram - A Wireless Local Area Network 2

Microwave Basic Blocks 7

Example of the Microwave application systems 9

Operation of HBT 13

A two-port network with general source and load impedances 20

The general transistor amplifier circuit. 22

Flow chart of whole project. 25

Block diagram of an amplifier circuit 27

Transistor BFP640 27

Graph of Noise Figure, Tested at Room Temperature 28.

Stability Factor and Stability Measure 29

LNA Gain Compression at 2441 MHz 3 0

S-parameters (1~211~) for the frequency 2.4GHz 3 0

Flowchart for simulation process 3 1

Schematic diagram for DC bias circuit 3 1

Flowchart for fabrication process 34

Layout of LNA circuit using ADS2004 A software 34

Layout of LNA circuit using Core1 Draw software 3 4

Ultraviolet equipment 35

LNA Circuit 36

Schematic Diagram for Transistor 3 8

Circuit for BJT Curve 3 9

BJT Curve 3 9

DC Bias Network 40

xiv

Input matching network schematic 42

Output matching network schematic. 42

LNA circuit schematic 44

Minimum noise figure 45

Forward gain, S2, 46

Input Return Loss (Sll) and Output Return Loss (S22) 47

Graph of Input Return Loss, S11 48

Input Return Loss, S1 I at 2.4GHz using Network Analyzer 49

Graph of Output Return Loss, S22 5 0

Output Return Loss, SZ2 at 2.4GHz using Network Analyzer 50

Graph of Input Return Loss,S, for Measurement and Simulation 5 1

Graph of Output Return LOSS,^^^ or Measurement and

Simulation 52

LIST OF ABBREVIATIONS

O K - ADS - CDMA - CMOS

Db - DBS - FR4 - GPS - GSM - HBT - HEMT - IB

Ic - IEC - IEEE - ISM

JFET - LNA - OFDM - PCB -

RF - SiGe - SMA

SNR - SONET -

Kelvin

Advanced Design System

Code-Division Multiple Access

Complementary Metal Oxide Semiconductor

Decibel

Direct Broadcast Satellite

Flame Retardant 4

Global Positioning System

Global System for Mobile

Heterojunction Bipolar Transistor

High Electron Mobility Transistor

Base Current

Collector Current

International Electrotechnical Commission

Electrical and Electronics Engineers

Industrial Scientific and Medical

Junction Gate Field-Effect Transistor

Low Noise Amplifier

Orthogonal Frequency Division Multiplexing

Printed Circuit Board

Radio Frequency

Silicon Germinium

SubMiniature version A

Signal to Noise Ratio

Synchronous Optical Network

Scatter Parameters

xvi

Zin

Zin

- Ultra-High Frequency

Ultra Violet

- Base Emitter Voltage

- Collector Emitter Voltage

- Impedance

- Input impedance

- Normalize value of input impedance

Load impedance

Characteristic impedance

Transformer impedance

Ohm

xvii

LIST OF APPENDICES

NO TITLE PAGE

NPN Silicon Germanium RF Transistor (BFP640) data sheet 59

Application note of the SiGe BFP640 as a 2.4GHz Low Noise

Amplifier 67

Measurement process 6 8

Circuit connection with the Network Analyzer 6 8

Connection between circuit and power supply. 69

Equipment for measurement process 69

Article of Low Noise Amplifier using BFP640 transistor 70

Article from IEEE 74

CHAPTER I

INTRODUCTION

1.1 Introduction

In a receiver design it is critical to have a good front end in order to have

good overall system performance. Among the front end components, the Low Noise

Amplifier, or LNA is very important in setting the noise figure of the entire system.

Low noise amplifiers represent one of the basic building blocks of the

communication system. The purpose of the LNA is to amplify the received signal to

acceptable levels while minimizing the noise it adds. Figure 1 shows a system level

diagram of the wireless local area network. The reduction in the signal due to losses

during transmission, reception and power dissipation in circuit components must be

compensated by using a device to provide sufficient gain for the receiver circuit.[6]

Figure 1.1 : System Level Diagram - A Wireless Local Area Network

The approach taken to design the amplifier involves a series of chronological

steps. No design is complete without some desired goals. The design specifications

for the low noise amplifier were as follows:[6]

a) Gain > 20 dB

b) Noise Figure < 1.5 dB

c) Use microstrip - matching networks

d) S1 and Sz2.<-15dB

1.2 Research Background

Over the past number of years, there is rapid changing in low noise

technology. From early 1980s, the achievements of technological innovations

especially in low noise technology not only improved devices, subsystems and

systems, but also increased the demand in new market. Thus, high performances as

well as low cost in fabrication make designer task more challenging.[7]

Although Low Noise Amplifier (LNA) performance was extremely good

nowadays, the design engineer still had to make some complex system trades. Many

LNA were large, heavy and consumed a lot of power. For an example in satellite

ground terminals, low noise performance, lighter weight, low power and high

reliability of LNA are required. Unfortunately, it is not always achieved because of

limitation in some factors.[7]

The bipolar junction transistor was the first solid-state active device to

provide practical gain and Noise Figure (F) at microwave frequencies. Then,

Silicon-Germanium (SiGe) Heterobipolar technology has generated worldwide

interest for digital, analog and RF applications because it combines the transistor

performance of 111-V technologies with the manufacturability, high yield and low

cost associated with conventional silicon integrated circuit (IC) fabrication. At

present, SiGe technology development is mainly focused on NPN SiGe

Heterobipolar transistors. [8]

From random processes such as the flow of charges or holes in an electron

tube or solid-state device, propagation through the ionosphere or other ionized gas

and the thermal vibration in any component at a temperature above absolute zero will

produce some noise. Noise can be passed into a microwave system from external

sources or generated within the system itself. In either case the noise level of the

system sets the lower limit on the strength of a signal that can be detected in the

presence of the noise. Thus, it is generally desired to minimize the residual noise

level of communication receiver or radar to achieve the best performance [2]. Since

the noise figure is the measured of receiver noise, it is important to obtained low

noise figure as possible.

This project is concentrate on designing low noise amplifier, which has

operating frequency at 2.4GHz. Wireless networking using the unlicensed 2.4-

2.5GHz frequency band is the most popular form of radio based networking. The

range of kit is massive with many hundreds of competitive kit available from simple

PCMCIA cards for notebook computers up to powerful bridging units designed to

link buildings.

1.3 Problem Statement

There are several problems with the current low noise amplifier system. In

reality, wireless channel and the receiver circuit add noise. If noise become large

enough compared to the desired signal, an error will occur. Then, most of the

transistor is unable to handle higher noise and cannot operate at higher frequency.

Another problem is low noise amplifier usually implies RFIwireless applications.

But noise still a critical consideration for lower frequency analog applications. . In

order to avoid this, the purpose of this project is produced. To select the appropriate

amplifier, firstly, understanding the noise parameters for a particular application are

needed and the amplifier need to be determined whether the amplifier is suitable or

not for this project.

1.4 Objectives

The objectives of the project are:

a) to study the characteristic and the specification of low noise amplifier

(LNA), specifically on LNA 2.4GHz application and wireless

applications.

b) to design and simulate a low noise amplifier 2.4GHz using Microwave

design software with varies of parameters.

c) to fabricate and develop a low noise amplifier 2.4GHz using microstrip

technology.

d) to learn and practice technical skills to overcome problems occurred in

implementing the project.

1.5 Scopes of Work

This project is divided into several parts. Firstly, design and simulation part.

This project will design WLAN LNA 2.4GHz. ADS2004 A is used in order to get the

require results which are close to theoretical results. Secondly, the fabrication

process will be done by using Microstrip, Printed Circuit Board (PCB) laminate like

standard low cost Flame Retardant 4 (FR4), SubMiniature version A (SMA)

connector, Aluminum sheet and etching facilities. Lastly, testing and measurement

part, this will include noise figure and gain of the circuit. The performance of the

designed amplifier is verified on the board by using RF test equipment such as

network analyzer and function generator.

1.6 Thesis Structure

This thesis is divided into five chapters and covered the research overview for

LNA circuit design. Chapter 2 reports the literature review of the basic concepts in

LNA circuit design. Chapter 3 described project methodology and development on

how the design, simulation and fabrication process. The Advance Design System

(ADS) software was used in order to design and simulate. The simulation and

measurement results are reported in Chapter IV known as result. Chapter IV also

discussed result fiom simulation and measurement. Chapter V concluded the

research work and give suggestions for future development of the research project.

CHAPTER I1

LITERATURE REVIEW

2.1 Low Noise Amplifier

The low noise amplifier (LNA) is a special type of electronic amplifier or

amplifier used in communication systems to amplify very weak signals captured by

an antenna. It is often located very close to the antenna. If the LNA is located close

to the antenna, then losses in the feedline become less critical. This "active antenna"

arrangement is frequently used in microwave systems like Global Positioning System

(GPS), because coaxial cable feedline is very lossy at microwave frequencies.

It is a key component, which is placed at the front-end of a radio receiver

circuit. Per Friis' formula, the overall noise figure of the receiver front-end is

dominated by the first few stages.

Using a LNA, the noise of all the subsequent stages is reduced by the gain of

the LNA and the noise of the LNA is injected directly into the received signal. Thus,

it is necessary for a LNA to boost the desired signal power while adding as little

noise and distortion as possible, so that the retrieval of this signal is possible in the

later stages in the system. [l l]

For low noise the amplifier needs to have a high amplification in its first

stage. Therefore Junction Gate Field-Effect Transistor (JFET), High Electron

Mobility Transistor (HEMT) or Heterojunction Bipolar Transistor (Hl3T) is used and

distributed amplifiers could be used. They are driven in a high current regime, which

is not energy efficient, but reduces the relative amount of shot noise. Input and

output matching circuits for narrow band circuits enhance the gain (see gain-

bandwidth product) and do not use resistors, as these will add noise. Biasing is done

by large resistors, because energy efficiency is not needed, and a large resistor

prevents leakage of the weak signal out of the signal path or noise into the signal

path. The application of LNA is shown on Figure 2.1 (basic Radio Frequency (RF)

block consists of nine function blocks).

RF Front-end Basics

Figure 2.1 : Microwave Basic Blocks

2.2 Microwaves

Microwaves are electromagnetic waves with wavelengths shorter than one

meter and longer than one millimeter, or frequencies between 300 megahertz and 300

gigahertz.

Apparatus and techniques may be described as "microwave" when the

wavelengths of signals are roughly the same as the dimensions of the equipment, so

that lumped-element circuit theory is inaccurate. As a consequence, practical

microwave technique tends to move away from the discrete resistors, capacitors, and

inductors used with lower frequency radio waves. Instead, distributed circuit